In today's touch control technology, taking tablet computers or smart phones as examples, controls are initiated through touching or sliding operations on a panel of an apparatus through one or multiple user's fingertip or pen like object which is held by the user. Alternatively, in addition to the touch panels, two or more camera lenses can be utilized to obtain the relative distances of the objects within a scene though a parallax method. However, if a distance detecting function with high accuracy is to be obtained under a short distance, taking double camera lens as example, the resolution of the distance recognition is positively correlated with the distance between the camera lenses, so that it increases the difficulty of reducing the volume of the whole system.
Furthermore, an additional detection light may be emitted onto the scene that is to be measured, and distances may be determined through the time-of-flight method or the variations of the projected structured light. By using the time-of-flight method as example, an electrical circuit for processing the high frequency signal is required to determine the distance of an object at close range due to the high speed characteristic of the speed of light. Furthermore, additional light and projecting apparatus are required in the method of projecting structured light. Hence, it is more difficult to meet the requirements of low energy consumption and system volume reduction. Although an effect of human and machine interaction is achieved through the variations of the position of the reflected light after the scanning of the scene with additional light source. However, the same problem exists as the method of projecting structured light.
Though scene is captured multiple times by utilizing a single lens, and distance can be determined through the feedback signal of an auto-focusing apparatus. However, auto-focusing generally requires a period of time to complete, and unable to satisfy a real-time human and machine interaction requirement.